Elevator safety device.



N0. 846F613. PATENTED MAR. 12, 1907.

0. R. PRATT.

ELEVATOR SAFETY DEVICE.

APPLIOATION FILED MAR. 27,1905.

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guide means (not shown) and to be raised scription of the working UNITEDSTATES PATENT oEEIoE; 1

oH RLES a. PRATT, or MoNToLAm, NEW JERSEY, ASSIGNOR To ROBERT M.OURRIER, or BOSTON, MASSACHUSETTS.

Specification of Letters Patent.

Patented March 12, 1907.

Application filed March 27, 1905. Serial No. 252,150;

To all whom it may concern.-

Be it known that 1, CHARLES R. PRATT, a citizen of the United States,residing at Montclair, in the county of Essex and State of New Jersey,have invented certain new and useful Improvements in Elevator SafetyDevices; and I do hereby declare the following to be a full, clear, andexact description of the invention, such as will enable others skilledin the art to which it appertains to make and use the same, referencebeing had to the accompanying drawings, and to letters of referencemarked thereon, whichform a part of this specification.

This invention relates to elevators, and more articularly to the safetymeans employe for preventing the elevator from falling to the bottom ofthe shaft in case the supporting-cables break or other accident happens.

The objects of the invention are to simplify and cheapen thefriction-rails which are adapted to be engaged by the gripping meansupon the bottom of the car; to provide tension-strips which shall be aneflicient substitute for the steel or woodrails, castiron racks, &c.,which have been used heretofore; to provide, improved gripping means forengaging the tension-strips, and to obtain other advantages and results,some of'which may be referred to in connection with-the departs. Theinvention consists in the improved :safety device for elevators and inthe arrangements and combinations of parts of the seam, allsubstantially as will be hereinafter Set forth and finally embraced inthe clauses of the claim.

Referring to the accompanying drawings, in which like letters ofreference indicate corresponding parts in each of the several figures,Figure 1 is a side elevation of an elevator-car and its safety-deviceattachments complete. Fig. 2 is a rear elevation of the safety-devicemechanism at the bottom of the car. Fig. 3 is a view looking upward"from beneath the car and showing the said mechanism partly in centrallongitudinal section as upon line 00 Fig. 2.

In said drawings, 2 indicates an elevatorcar of any well-knownconstruction adapted to move vertically between any ordinary -sion,

and lowered by any usual means. (Not shown.) At each of the oppositelateral sides of the car is arranged a pair of vertical tension-strips 33 which are fastened at their upper ends, as at 4 4, to an I-beam 5 andat their lower ends are held by eye bolts 6 6 in a frame 7 and whichbolts have nuts 8, by which Said strips 3 can be tightened to thedesired tension. Each of said strips 3 is a flat cold-rolled piece ofsteel possessing great tensile strength and having a hard smooth regularsurface. These extend from one end to the other of the hoistway, so thatthere are neither welds nor joints of any kind and while I have beenunable to find such strips already upon the market I am assured that thesame can be manufactured. Only the upper and lower extremities of thestrips are held by the fastening means above described, and by thesefastening means the strips can be brought under any desired tenso that Ihave termed them tensionstrips. Obviously there must be sufficienttension to prevent lateral sagging of the strips, so they will notunduly engage the gripping means when idle. At the same time a veryconsiderable tension will not prevent sufiicient yielding againstpressure of the idle gripping means to obviate undue friction. The saidstrips are exposed on all sides, except as inclosed by the grippingmeans, and so are free to move or yield in any lateral direction.

'It will be understood that where old-fashioned wood rails are removedfrom the elevator-shaft in a building already completed and in use it isextremely difficult to insert new rails, because of their length andstiflness. I have therefore provided my improved tension-stripsparticularly for use in such places, the strip being such that it can berolled into coils for shipment and brought into the hoistway and thenstraightened out by the mere act of unwinding, and thus assume itsnormal extended position for use. Obviously great convenience is securedand ease of handling and shipping and the substitution of other brakemeans for the old fashioned wood rails is rendered feasible in a greatmany cases where it could not otherwise be done.

Upon the bottom of the car I arrange means adapted to frictionally gripthe said strips 3 3 in case of accident and bring the car to a gradualstop to prevent its dropping to the bottom of the shaft. These grippingmeans are, as usual, operated by means of a rope 9, which is anchored atits ends to drum upon the bottom of the car and adapted to Wind inopposite directions on said drum, the intermediate or middle portion ofthe rope extending upward over a governor-sheave 11, downward, as at 12,over an idle tension-sheave 13, and thence back to the drum 10. Undernormal conditions a catch 39, shown located upon the top of the car 2,serves to hold the rope 9, so that it turns the sheaves 11 13 idly intheir bearings instead of rotating the drum 10. If, however, an accidenthappens, so that the car starts to drop and the governor-sheave 11rotates at a speed above the normal, centrifugal weights 14 on saidsheave fly outward and trip a latch 15 to release the same and permit amovable jaw 16 to clamp the rope tightly against a cooperating fixed jaw17. Obviously this stops movement of the intermediate portion of therope, the said catch 39 slipping upon it, and the drum '10 begins toturn, one end of the rope unwinding therefrom and the other winding uponthe drum.

Upon the bottom of the car, adjacent to the op osite lateral sidesthereof, are fixed depen ing brackets 18 18, each of which has at itsextremity an outwardly-projecting horizontal jaw 19. Said jaws 19 areeach preferably T-shaped in plan, the stem 20 lying between thefruition-strips 3 3 and the arms 21 21 being adapted to hook loosely onearound each of the said strips 3 3, as shown in Fig. 3.. Preferably arod 22 extends between the lower ends or jaws 19 of the two brackets 18to brace said brackets, said rod having threaded ends 23, which screwinto said jaw-pieces. Upon the said rod 22 is a hollow shaft or sleeve24, loose from the rod and b eing oppositely threaded at its extremitiesthat is, one end 25 having a right-hand thread and the other end 26having a left-hand thread. Each of the said threaded ends of the hollowshaft 24 enters a correspondingly-threaded socket 27 (or 28) of an innerjaw 29, adapted to cooperate with the outer jaws 19, above described, ingripping the tension-strips 3 3. Each of said aws 29 has a slidingbearing, as at 30, upon the rod 22 and is provided withoutwardly-projecting vertical arms 31 31, which lie on either side ofthe stem 20- of the T-shaped outer jaw 19 and are adapted at their endsto, engage the inner sides of the tension-strips 31 3, lying within thearms 21 of said outer jaw. The said hollow shaft 24 is j ournaled inbearings 32 at the ends of arms 33, projecting from the brackets 34,which support the. drum 10, before described, as shown in Figs. 2 and 3,and obviously upon turning said shaft 24 the movable jaws29 will be bothmoved toward or away from the outer fixed jaws 19, according to thedirection of turning. To rotate the said hollow shaft 24, asprocket-wheel 35 is fixed upon the shaft and connected, as by a chain36, with a driving-sprocket 37, fast upon the same shaft 38 as the drum10 is fixed upon. The winding of the rope ends upon the drum 10 is thensuch that when the car drops, as above described, the said drum will beturned in a direction to transmit motion through its shaft 38,sprocket-wheel 37, chain 36 and sprocket 35 to rotate the hollow shaft24 in aproper direction to force the movable jaws 29' apart from eachother into engagement with the tension-strips 3 3. The friction thusproduced upon the tension-strips suflices to stop the car, and by meansof the gears 35 37 the time of effecting such friction is so regulatedthat the car is not stopped with undue abruptness.

Obviously my improved friction-strips are much cheaper than steel orwood rails, castiron racks, or the like and are much more readily andeasily installed. At the same time my improved gripping means enablessure and eflicient hold to be had on said strips. Furthermore, becauseof the flexibility of the friction-strips the clearance of thegripping-jaws need not be so great in order to avoid undue wear.

Having thus, described the .invention,what I claim as new is 1. In asafety device for elevators, a flat cold-rolled or drawn tension-stripof metal extending longitudinally of the hoistway from end to endthereof, said strip, being flexible and adapted to be coiled or rolledupon itself, means for engaging the extremities of said tension-stripand stretching the same, and gripping means upon the car to engage saidstrip.

2. In a safety device for elevators, a plurality of cold-rolled or drawnsteel tensionstrips arranged longitudinally of the hoistway at the sidesof the car and being continu ous or free from joints or welds. from oneend of the hoistway to the other, said strips being flexible and adaptedto be coiled or wound up for transportation, means sup orting saidstrips by their opposite ends wliile leaving them freely exposed on allsides andadapted to bring the said strips under tension as; desired, andmeans adapted to be carried by the car to inclose or surround saidstrips and exert a gripping action thereon. Y

3. Ina safety device for elevators, tensionstrips arranged in thehoistway on opposite sides of the car, fixed gripping-jaws mounted onthe car and lying outside said tensionstrips, a rigid rod extendingbetween said jaws, a hollow shaft mounted on said rod between said fixedjaws, a rightehand threaded nut on one end and a left-hand threaded nuton the other end of said hollow shaft, movhave'hereunto set my hand this25th day of ab? jaws niiountkedfone 3n each oglsaid nuts March, 1905. ana a te to e orce outwar ya ainst the said iiXed jaws, and means automatically CHARLES T operated by the falling of the car for rotatingWitnesses: said hollow shaft. CHARLES H. PELL,

In testimony that I claim the foregoing I RUssELL M. EVERETT.

